Pub Date : 2024-10-21DOI: 10.1016/j.vacuum.2024.113759
Tianshi Hu, Benfu Wang, Xiubo Tian, Chunzhi Gong
The PVD deposition of films with excellent surface properties has been a persistent area of research. In this paper, bipolar high power impulse magnetron sputtering with small target-substrate distance is proposed, and ultra-hard Cr films have been deposited with a higher rate in tubes. The microstructure and mechanical properties of the films were characterized using X-ray diffraction, scanning electron microscopy, nanoindentation and scratch test, and compared with films prepared under conventional conditions. With target-substrate distance of 7.5 mm, the ultrafine columnar structure is fabricated due to intensive glow discharge and direct particle-bombardment in high-density plasma. The small grain size of 7.4 ± 0.3 nm is observed although deposition rate as high as 10 μm/hr. The nanohardness of the films reaches 19.94 ± 1.14 GPa, much higher than that reported in the literatures. Meanwhile, the adhesion between film and substrate may be as high as 77 ± 5 N.
{"title":"Ultrafast deposition of ultrahard Cr films in tubes by bipolar-HiPIMS with small target-substrate distance","authors":"Tianshi Hu, Benfu Wang, Xiubo Tian, Chunzhi Gong","doi":"10.1016/j.vacuum.2024.113759","DOIUrl":"10.1016/j.vacuum.2024.113759","url":null,"abstract":"<div><div>The PVD deposition of films with excellent surface properties has been a persistent area of research. In this paper, bipolar high power impulse magnetron sputtering with small target-substrate distance is proposed, and ultra-hard Cr films have been deposited with a higher rate in tubes. The microstructure and mechanical properties of the films were characterized using X-ray diffraction, scanning electron microscopy, nanoindentation and scratch test, and compared with films prepared under conventional conditions. With target-substrate distance of 7.5 mm, the ultrafine columnar structure is fabricated due to intensive glow discharge and direct particle-bombardment in high-density plasma. The small grain size of 7.4 ± 0.3 nm is observed although deposition rate as high as 10 μm/hr. The nanohardness of the films reaches 19.94 ± 1.14 GPa, much higher than that reported in the literatures. Meanwhile, the adhesion between film and substrate may be as high as 77 ± 5 N.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113759"},"PeriodicalIF":3.8,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142530749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-21DOI: 10.1016/j.vacuum.2024.113760
Feng Chen , Lanqing Mo , Fei Hu , Wangyun Li , Song Wei
In order to evaluate the vibration resistance of Sn58Bi solder in serving electronic devices, the damping capacities of Sn58Bi solders after thermomigration (TM) test at a temperature gradient of 2000 °C/cm for different time (0, 120, 360, 720, and 1440 h) were characterized under electric current stressing (0, 4.0, and 8.0 A). The results indicate that the phase segregation of TM-tested Sn58Bi solders determines the damping performance of solders. The Bi-rich layer thickens with prolonged TM time and migrates in the direction from high temperature to low temperature. Both the critical strains (the values of dislocation getting rid of pining points) of strain-amplitude-related damping capacity curves increases with prolonged TM time, while decreases with increasing electric current. Moreover, both strain-amplitude-related and temperature-related damping capacity shows a general decreasing trend with prolonged TM time, while increases exponentially with increasing electric current. In addition, the damping mechanism changes from dislocation motion to phase boundary sliding with increasing temperature, and the transition temperature decreases with increasing current but generally increases with TM time.
{"title":"Synergistic effect of thermomigration and electric current stressing on damping capacity of Sn58Bi solder","authors":"Feng Chen , Lanqing Mo , Fei Hu , Wangyun Li , Song Wei","doi":"10.1016/j.vacuum.2024.113760","DOIUrl":"10.1016/j.vacuum.2024.113760","url":null,"abstract":"<div><div>In order to evaluate the vibration resistance of Sn58Bi solder in serving electronic devices, the damping capacities of Sn58Bi solders after thermomigration (TM) test at a temperature gradient of 2000 °C/cm for different time (0, 120, 360, 720, and 1440 h) were characterized under electric current stressing (0, 4.0, and 8.0 A). The results indicate that the phase segregation of TM-tested Sn58Bi solders determines the damping performance of solders. The Bi-rich layer thickens with prolonged TM time and migrates in the direction from high temperature to low temperature. Both the critical strains (the values of dislocation getting rid of pining points) of strain-amplitude-related damping capacity curves increases with prolonged TM time, while decreases with increasing electric current. Moreover, both strain-amplitude-related and temperature-related damping capacity shows a general decreasing trend with prolonged TM time, while increases exponentially with increasing electric current. In addition, the damping mechanism changes from dislocation motion to phase boundary sliding with increasing temperature, and the transition temperature decreases with increasing current but generally increases with TM time.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113760"},"PeriodicalIF":3.8,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142530838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-20DOI: 10.1016/j.vacuum.2024.113757
Penghui Lei , Ni Jiang , Jiannan Hao , Qing Peng , Pan Qi , Fangjie Shi , Yuhua Hang , Qianwu Li , Chao Ye
In order to investigate the synergistic effect of thermal aging and hydrogen, Z3CN20.09M duplex stainless steels (DSS) were thermal aged at 400 °C and then the irradiated by hydrogen ions. Due to the segregation of the Fe and Cr elements induced by spinodal decomposition, the nanohardness of the ferrite phase increased after thermal aging process. The irradiation effects by hydrogen ion could further increase the nanohardness of the damage region. But the {011}<111> slip system structures formed by the irradiation significantly suppressed the hardening effects of the ions irradiation induced dislocations and spinodal decomposition induced element segregation. During the in-situ transmission electron microscopy (TEM) tensile process, severe deformation occurred and extended along a slip band that ran diagonally across the entire sample region. At last, a cracking formed at the deformation center area and propagated along the crack tip towards the irradiation damage side, ultimately leading to the sample fracture. This study serves as a valuable reference for improving the properties of Z3CN20.09M DSS utilized in nuclear plants.
为了研究热时效和氢的协同效应，Z3CN20.09M 双相不锈钢（DSS）在 400 °C 下进行热时效，然后用氢离子进行辐照。由于旋光分解引起的铁和铬元素偏析，铁素体相的纳米硬度在热时效过程后有所增加。氢离子的辐照效应可进一步提高损伤区域的纳米硬度。但辐照形成的{011}<111>滑移系结构明显抑制了离子辐照诱导的位错和旋光分解诱导的元素偏析的硬化效应。在原位透射电子显微镜（TEM）拉伸过程中，发生了严重的变形，并沿着一条斜向贯穿整个样品区域的滑移带延伸。最后，在变形中心区域形成裂纹，并沿着裂纹尖端向辐照损伤侧传播，最终导致样品断裂。这项研究对提高核电站使用的 Z3CN20.09M DSS 的性能具有重要参考价值。
{"title":"Effect of hydrogen ion irradiation on the mechanical properties of thermally aged Z3CN20.09M duplex stainless steel","authors":"Penghui Lei , Ni Jiang , Jiannan Hao , Qing Peng , Pan Qi , Fangjie Shi , Yuhua Hang , Qianwu Li , Chao Ye","doi":"10.1016/j.vacuum.2024.113757","DOIUrl":"10.1016/j.vacuum.2024.113757","url":null,"abstract":"<div><div>In order to investigate the synergistic effect of thermal aging and hydrogen, Z3CN20.09M duplex stainless steels (DSS) were thermal aged at 400 °C and then the irradiated by hydrogen ions. Due to the segregation of the Fe and Cr elements induced by spinodal decomposition, the nanohardness of the ferrite phase increased after thermal aging process. The irradiation effects by hydrogen ion could further increase the nanohardness of the damage region. But the {011}<111> slip system structures formed by the irradiation significantly suppressed the hardening effects of the ions irradiation induced dislocations and spinodal decomposition induced element segregation. During the in-situ transmission electron microscopy (TEM) tensile process, severe deformation occurred and extended along a slip band that ran diagonally across the entire sample region. At last, a cracking formed at the deformation center area and propagated along the crack tip towards the irradiation damage side, ultimately leading to the sample fracture. This study serves as a valuable reference for improving the properties of Z3CN20.09M DSS utilized in nuclear plants.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113757"},"PeriodicalIF":3.8,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142530840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-19DOI: 10.1016/j.vacuum.2024.113756
Guoxu Zheng , Xinzhe Huang , Minqiang Xu , Liwei Mao , Qian Zhang , Zhuo Yuan , Zhiwei Liu , Mingxin Song
In this paper, SnO2/Ni2SnO4 heterojunctions were grown on NF by a simple secondary hydrothermal method. DFT-based calculations show that the SnO2/Ni2SnO4 heterojunction has excellent thermal stability with a low band gap (1.7 eV) and Li+ diffusion barrier (0.822 eV), which is attributed to the generation of an internal electric field that promotes carrier transport. Electrochemical tests showed that the initial capacity of SnO2/Ni2SnO4/NF was 1401 mAh g−1, and its capacity was 970 mAh g−1 after 200 charge/discharge cycles, which is attributed to metal-oxygen bonds at the interface and a special microsphere structure to improve the stability of the materials. In addition, the electrochemical behavior of SnO2/Ni2SnO4/NF is dominated by capacitive behavior, resulting in excellent rate performance. The synthesis of SnO2/Ni2SnO4/NF provides a reference for designing other heterojunctions anode materials.
{"title":"Study of internal electric field and interface bonding engineered heterojunction for high stability lithium-ion battery anode","authors":"Guoxu Zheng , Xinzhe Huang , Minqiang Xu , Liwei Mao , Qian Zhang , Zhuo Yuan , Zhiwei Liu , Mingxin Song","doi":"10.1016/j.vacuum.2024.113756","DOIUrl":"10.1016/j.vacuum.2024.113756","url":null,"abstract":"<div><div>In this paper, SnO<sub>2</sub>/Ni<sub>2</sub>SnO<sub>4</sub> heterojunctions were grown on NF by a simple secondary hydrothermal method. DFT-based calculations show that the SnO<sub>2</sub>/Ni<sub>2</sub>SnO<sub>4</sub> heterojunction has excellent thermal stability with a low band gap (1.7 eV) and Li<sup>+</sup> diffusion barrier (0.822 eV), which is attributed to the generation of an internal electric field that promotes carrier transport. Electrochemical tests showed that the initial capacity of SnO<sub>2</sub>/Ni<sub>2</sub>SnO<sub>4</sub>/NF was 1401 mAh g<sup>−1</sup>, and its capacity was 970 mAh g<sup>−1</sup> after 200 charge/discharge cycles, which is attributed to metal-oxygen bonds at the interface and a special microsphere structure to improve the stability of the materials. In addition, the electrochemical behavior of SnO<sub>2</sub>/Ni<sub>2</sub>SnO<sub>4</sub>/NF is dominated by capacitive behavior, resulting in excellent rate performance. The synthesis of SnO<sub>2</sub>/Ni<sub>2</sub>SnO<sub>4</sub>/NF provides a reference for designing other heterojunctions anode materials.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113756"},"PeriodicalIF":3.8,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-19DOI: 10.1016/j.vacuum.2024.113755
Hassan Javed, Kees Kolmeijer, Nick Klein, Jamie A. Trindell, Gregory Schneider, Rik V. Mom
During electrocatalytic reactions, the electrode, adsorbates, electrolyte ions, and solvent molecules at the electrode-electrolyte interface each play an important role. Electrochemical X-ray photoelectron spectroscopy (XPS) holds great promise for deciphering these roles, providing the oxidation state or bonding environment of every element present at the interface. However, combining the vacuum required for XPS with the wet environment needed for electrochemistry constitutes a technical challenge, requiring purpose-built instrumentation and spectro-electrochemical cell design. Here, we present a laboratory-based electrochemical XPS instrument optimized for operando studies on nano-structured electrocatalysts. The core of the system is a 3D printed spectro-electrochemical cell containing a membrane-electrode-graphene assembly. We show that this design enables us to probe the electrode surface, interfacial water, and interfacial ions under well-defined potential control. Meanwhile, the introduction of a mesoporous membrane into the assembly enables the transport of any molecular or ionic reactant towards the working electrode, opening the way to study any aqueous phase electrocatalytic system using laboratory-based electrochemical XPS. We exemplify this for the oxygen reduction reaction.
在电催化反应过程中，电极、吸附剂、电解质离子以及电极-电解质界面上的溶剂分子都发挥着重要作用。电化学 X 射线光电子能谱（XPS）可提供界面上每种元素的氧化态或成键环境，为破译这些作用带来了巨大希望。然而，将 XPS 所需的真空与电化学所需的潮湿环境相结合是一项技术挑战，需要专门设计仪器和光谱电化学池。在此，我们介绍一种基于实验室的电化学 XPS 仪器，该仪器针对纳米结构电催化剂的操作研究进行了优化。该系统的核心是一个 3D 打印的光谱电化学池，其中包含一个膜-电极-石墨烯组件。我们的研究表明，这种设计使我们能够在明确的电位控制下探测电极表面、界面水和界面离子。同时，在组件中引入介孔膜可使任何分子或离子反应物向工作电极传输，从而为利用实验室电化学 XPS 研究任何水相电催化系统开辟了道路。我们以氧还原反应为例进行说明。
{"title":"A laboratory-based electrochemical NAP-XPS system for operando electrocatalysis studies","authors":"Hassan Javed, Kees Kolmeijer, Nick Klein, Jamie A. Trindell, Gregory Schneider, Rik V. Mom","doi":"10.1016/j.vacuum.2024.113755","DOIUrl":"10.1016/j.vacuum.2024.113755","url":null,"abstract":"<div><div>During electrocatalytic reactions, the electrode, adsorbates, electrolyte ions, and solvent molecules at the electrode-electrolyte interface each play an important role. Electrochemical X-ray photoelectron spectroscopy (XPS) holds great promise for deciphering these roles, providing the oxidation state or bonding environment of every element present at the interface. However, combining the vacuum required for XPS with the wet environment needed for electrochemistry constitutes a technical challenge, requiring purpose-built instrumentation and spectro-electrochemical cell design. Here, we present a laboratory-based electrochemical XPS instrument optimized for <em>operando</em> studies on nano-structured electrocatalysts. The core of the system is a 3D printed spectro-electrochemical cell containing a membrane-electrode-graphene assembly. We show that this design enables us to probe the electrode surface, interfacial water, and interfacial ions under well-defined potential control. Meanwhile, the introduction of a mesoporous membrane into the assembly enables the transport of any molecular or ionic reactant towards the working electrode, opening the way to study any aqueous phase electrocatalytic system using laboratory-based electrochemical XPS. We exemplify this for the oxygen reduction reaction.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113755"},"PeriodicalIF":3.8,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-18DOI: 10.1016/j.vacuum.2024.113737
A.I. Il'in , V.K. Egorov , A.A. Ivanov
Epitaxial YBa2Cu3O7‒δ (YBCO) films 150–200 and 300 nm thick, respectively, were deposited on SrTiO3 (100) substrates by pulsed laser deposition at different conditions: with and without using the velocity filtration technique. The films have T(R = 0) in the range of 77.4–87 R(T) depending on the conditions of deposition from one target with YBa2Cu3O6.8 composition. The films contain Zn, Sr, Pd, Ag and Ti impurity elements obtained from the target (a total of no more than 2 at. %). Data of the film resistance temperature dependences, X-ray phase analysis, analysis of X-ray fluorescence (XRF) spectra and study of the surface relief by SEM methods revealed the nonuniform distributions of impurity and matrix Y, Ba, Cu elements over the film depth. Impurity concentrations near the surface lead to the formation of faceted spiral pyramids on the surface, which probably evolve into large elongated particles according to the Ostwald mechanism. This knowledge is practically important for optimizing pulsed laser deposition technologies and creating 2D instruments and devices for studying physical phenomena.
{"title":"Variations of the elemental composition distribution over the thickness of YBa2Cu3O7-δ thin films obtained by pulsed laser deposition from one target","authors":"A.I. Il'in , V.K. Egorov , A.A. Ivanov","doi":"10.1016/j.vacuum.2024.113737","DOIUrl":"10.1016/j.vacuum.2024.113737","url":null,"abstract":"<div><div>Epitaxial YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7‒δ</sub> (YBCO) films 150–200 and 300 nm thick, respectively, were deposited on SrTiO<sub>3</sub> (100) substrates by pulsed laser deposition at different conditions: with and without using the velocity filtration technique. The films have T(R = 0) in the range of 77.4–87 R(T) depending on the conditions of deposition from one target with YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6.8</sub> composition. The films contain Zn, Sr, Pd, Ag and Ti impurity elements obtained from the target (a total of no more than 2 at. %). Data of the film resistance temperature dependences, X-ray phase analysis, analysis of X-ray fluorescence (XRF) spectra and study of the surface relief by SEM methods revealed the nonuniform distributions of impurity and matrix Y, Ba, Cu elements over the film depth. Impurity concentrations near the surface lead to the formation of faceted spiral pyramids on the surface, which probably evolve into large elongated particles according to the Ostwald mechanism. This knowledge is practically important for optimizing pulsed laser deposition technologies and creating 2D instruments and devices for studying physical phenomena.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113737"},"PeriodicalIF":3.8,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142530748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-18DOI: 10.1016/j.vacuum.2024.113751
Jessica D. Silva , Dilson S. Santos , Vicente T.L. Buono , Leandro A. Santos
TiNiCuNb shape memory alloys are a promising new class of materials with the potential to be applied as elastocaloric components. However, the mechanical processing of these alloys remains a challenge and new insights on this topic must enlighten the knowledge about this system. In this work, the effects of hot rolling on Ti46Ni38Cu10Nb6 alloy were investigated. The results showed that hot rolling leads to the increase of martensitic transformation temperatures and the formation of a matrix containing both B2 and B19 phases. The coarsening of the lamellar eutectic constituent was observed, and part of the β-Nb phase precipitated into the matrix after being dissolved due to hot work. Microstructural aspects and ultra-microhardness measurements suggest that dynamic recrystallization occurred during hot rolling.
{"title":"Influence of hot rolling on microstructure, mechanical properties, and martensitic transformation of TiNiCuNb shape memory alloy","authors":"Jessica D. Silva , Dilson S. Santos , Vicente T.L. Buono , Leandro A. Santos","doi":"10.1016/j.vacuum.2024.113751","DOIUrl":"10.1016/j.vacuum.2024.113751","url":null,"abstract":"<div><div>TiNiCuNb shape memory alloys are a promising new class of materials with the potential to be applied as elastocaloric components. However, the mechanical processing of these alloys remains a challenge and new insights on this topic must enlighten the knowledge about this system. In this work, the effects of hot rolling on Ti<sub>46</sub>Ni<sub>38</sub>Cu<sub>10</sub>Nb<sub>6</sub> alloy were investigated. The results showed that hot rolling leads to the increase of martensitic transformation temperatures and the formation of a matrix containing both B2 and B19 phases. The coarsening of the lamellar eutectic constituent was observed, and part of the β-Nb phase precipitated into the matrix after being dissolved due to hot work. Microstructural aspects and ultra-microhardness measurements suggest that dynamic recrystallization occurred during hot rolling.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"230 ","pages":"Article 113751"},"PeriodicalIF":3.8,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-18DOI: 10.1016/j.vacuum.2024.113728
Felix Sharipov , Irina Graur , Evelyne Salançon
A coaxial ion source produces an ion beam via field effect in a gas flow through a coaxial microchannel structure. Measuring the intensity of ion emission under an electric voltage condition reveals the pressure at the tip of the coaxial structure, where ionization occurs. The spatial resolution of the measurements is defined by the volume into which the position of the tip fits, here estimated as a cube with an edge of 10 m. The pressure at the tip is also obtained analytically as a function of the throughput through the coaxial structure. The theoretical and experimental pressure values reported in the present work are in agreement between them within the geometric uncertainties of the coaxial structure itself.
{"title":"Field ionization intensity used to measure local pressure in gas flows","authors":"Felix Sharipov , Irina Graur , Evelyne Salançon","doi":"10.1016/j.vacuum.2024.113728","DOIUrl":"10.1016/j.vacuum.2024.113728","url":null,"abstract":"<div><div>A coaxial ion source produces an ion beam via field effect in a gas flow through a coaxial microchannel structure. Measuring the intensity of ion emission under an electric voltage condition reveals the pressure at the tip of the coaxial structure, where ionization occurs. The spatial resolution of the measurements is defined by the volume into which the position of the tip fits, here estimated as a cube with an edge of 10 <span><math><mi>μ</mi></math></span>m. The pressure at the tip is also obtained analytically as a function of the throughput through the coaxial structure. The theoretical and experimental pressure values reported in the present work are in agreement between them within the geometric uncertainties of the coaxial structure itself.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113728"},"PeriodicalIF":3.8,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142530839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-16DOI: 10.1016/j.vacuum.2024.113741
Wei Huang , Guangliang Xu , Jing Chen , Wei Shi , Yingchang Yang
Due to its distinctive two-dimensional planar structure, room temperature quantum Hall effect, and high strength, graphene has garnered significant interest in the fields of energy storage and conversion. In order to achieve high efficiency in the production of graphene, electrochemical peeling has been extensively investigated. Nevertheless, the intermolecular forces between graphite layers are disrupted during ion intercalation in solution, leading to inconsistent bonding forces and low yields. In order to address the issues above, this study introduces a novel bottom-up electrochemical peeling method, wherein graphite expansion occurs above the electrolyte. By preventing contact between the peeled graphene and the electrolyte, the oxidation of graphene is significantly minimized, resulting in a substantial yield of 88 %. At the current density of 1.0 A g−1, the Go-QAS displayed 225.5 F g−1, and kept about 220.2 F g−1 after 500 cycles. The well-designed bottom-up peeling process leads to graphene nanosheets with reduced structural degradation, high purity, and excellent conductivity. This technique is expected to introduce innovative concepts for the field.
由于其独特的二维平面结构、室温量子霍尔效应和高强度，石墨烯在能源存储和转换领域引起了极大的兴趣。为了实现石墨烯的高效生产，人们对电化学剥离进行了广泛研究。然而，在溶液中离子插层时，石墨层之间的分子间作用力会被破坏，导致结合力不一致和产量低。为了解决上述问题，本研究引入了一种自下而上的新型电化学剥离方法，即在电解液上方进行石墨膨胀。通过防止剥离后的石墨烯与电解质接触，石墨烯的氧化作用被大大降低，从而获得 88% 的高产率。在电流密度为 1.0 A g-1 时，Go-QAS 显示出 225.5 F g-1，并在 500 次循环后保持在 220.2 F g-1 左右。经过精心设计的自下而上的剥离过程可以获得结构退化程度低、纯度高、导电性能优异的石墨烯纳米片。这项技术有望为该领域引入创新概念。
{"title":"Bottom-up stripping of graphene with controlled oxidation behaviors towards supercapacitors energy storage","authors":"Wei Huang , Guangliang Xu , Jing Chen , Wei Shi , Yingchang Yang","doi":"10.1016/j.vacuum.2024.113741","DOIUrl":"10.1016/j.vacuum.2024.113741","url":null,"abstract":"<div><div>Due to its distinctive two-dimensional planar structure, room temperature quantum Hall effect, and high strength, graphene has garnered significant interest in the fields of energy storage and conversion. In order to achieve high efficiency in the production of graphene, electrochemical peeling has been extensively investigated. Nevertheless, the intermolecular forces between graphite layers are disrupted during ion intercalation in solution, leading to inconsistent bonding forces and low yields. In order to address the issues above, this study introduces a novel bottom-up electrochemical peeling method, wherein graphite expansion occurs above the electrolyte. By preventing contact between the peeled graphene and the electrolyte, the oxidation of graphene is significantly minimized, resulting in a substantial yield of 88 %. At the current density of 1.0 A g<sup>−1</sup>, the Go-QAS displayed 225.5 F g<sup>−1</sup>, and kept about 220.2 F g<sup>−1</sup> after 500 cycles. The well-designed bottom-up peeling process leads to graphene nanosheets with reduced structural degradation, high purity, and excellent conductivity. This technique is expected to introduce innovative concepts for the field.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"230 ","pages":"Article 113741"},"PeriodicalIF":3.8,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142539187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The RF-biased ion thruster applies radio-frequency (RF) power on the grid system, which can extract both ions and electrons to achieve self-neutralization. The performance of the RF-biased ion thruster is significantly influenced by the structure of the grid system and the discharge power since these factors play a crucial role in determining the focusing condition of the grid system. In this paper, the influence of discharge power and grid structure on the RF-biased ion thruster’s voltage parameters is investigated. According to the screen grid voltage waveform results under different discharge power and grid structure, the relationship between self-bias voltage and RF voltage is acquired. In order to explain the different waveform variations, the impacts of the direct impingement current as well as the oscillation of the upstream sheath voltage are considered in the theoretical calculation for self-bias voltage. It has been found that the opposite oscillation of the upstream sheath voltage is the primary reason for the decline in self-bias voltage. Moreover, the mechanisms through which discharge power and grid structure influence the self-bias voltage are explained in terms of their impact on upstream sheath oscillation. Several methods for increasing the self-bias voltage in RF-biased ion thrusters are also proposed.
{"title":"Influence of discharge power and grid structure on an RF-biased ion thruster","authors":"Jinyuan Yang, Siyuan Zhang, Yuliang Fu, Liwei Zhang, Chenxi Feng, Haolin Li, Guanjun Zhang, Anbang Sun","doi":"10.1016/j.vacuum.2024.113729","DOIUrl":"10.1016/j.vacuum.2024.113729","url":null,"abstract":"<div><div>The RF-biased ion thruster applies radio-frequency (RF) power on the grid system, which can extract both ions and electrons to achieve self-neutralization. The performance of the RF-biased ion thruster is significantly influenced by the structure of the grid system and the discharge power since these factors play a crucial role in determining the focusing condition of the grid system. In this paper, the influence of discharge power and grid structure on the RF-biased ion thruster’s voltage parameters is investigated. According to the screen grid voltage waveform results under different discharge power and grid structure, the relationship between self-bias voltage and RF voltage is acquired. In order to explain the different waveform variations, the impacts of the direct impingement current as well as the oscillation of the upstream sheath voltage are considered in the theoretical calculation for self-bias voltage. It has been found that the opposite oscillation of the upstream sheath voltage is the primary reason for the decline in self-bias voltage. Moreover, the mechanisms through which discharge power and grid structure influence the self-bias voltage are explained in terms of their impact on upstream sheath oscillation. Several methods for increasing the self-bias voltage in RF-biased ion thrusters are also proposed.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113729"},"PeriodicalIF":3.8,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142530835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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